Enhancement of lubricant addition agents effectiveness by correlating its molecular geometry with that of oleaginous base



United States Patent O ENHANCEMENT OF LUBRICANT ADDITION AGENT EFFECTEVENESS BY CORRELAT- ING ITS MOLECULAR GEOMETRY WITH THAT OF OLEAGENOUS BASE Herman E. Ries, In, Chicago, Ill., and Joseph Gabor,

Whiting, Ind, assigners to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed Jan. 18, 1967, Ser. No. 610,038

Int. Cl. C1011; 1/48, 3/42 US. Cl. 252-9 4 Claims ABSTRACT OF THE DISCLOSURE A lubricant for moving metal parts having as the oleaginous base solvent of the lubricant a petroleum fraction of the lubricating oil boiling range and lubricant addition agent solutes. The lubricant addition agent solutes have hydrocarbon moieties with hydrocarbon molecular geometry substantially similar to the hydrocarbon molecular geometry of the solvent.

BACKGROUND This invention applies broadly to the enhancing effectiveness of lubricant addition agents incorporated in oleaginous bases, especially oleaginous hydrocarbon fractions of petroleum, useful for the lubrication of metals products that must move with minimum friction loss in contact with one or more other metal parts. About to years ago the lubrication of moving metal parts in internal combustion engines such as automobile gasoline engines, diesel engines, engines operating with normally gaseous hydrocarbons as fuels, and two cycle engines could be satisfactorily lubricated with straight mineral oil. About 25 to 30 years ago with the development of internal combustion engines of greater power to weight ratios it was appreciated that lubrication with straight mineral oil was no longer adequate and there began the development of the concept of enhancing the lubricating ability of oleaginous materials by the use of lubricant addition agents such as anti-oxidants, anti-corrosion agents, detergents and dispersants. This lubricant addition agent concept has continued either side-by-side with or slightly ahead of the ever changing design and improvement of internal combustion engines to the present time when those internal combustion engines have through increased compression ratio, operating temperature and increased fuel combustion efficiency high power per weight and have been designed with closer and closer clearances between moving parts. Improvements in power transmission have also occurred over the past 25 to 30 years resulting not only in closer and closer clearances between moving parts but also in higher and higher pressures between cooperating power transmitting members such as power transmitting gears to also require lubricant compositions more efficient than straight mineral oils. Many of the same types of lubricant addition agents found to be useful for internal combustion engine lubrication have aiso been found to be useful for addition agents in lubricant compositions used to lubricate power transmitting means and other special types of addition agents have evolved for this changing power transmitting lubrication.

The basic ingredient for lubrication of internal combustion engines and power transmission means has been oleaginous fractions of varying viscosity characteristics of petroleum oil usually referred to in this art as lubricant oil base stocks. These lubricant oil base stocks are gen erally distillate fractions of petroleum oil residuum boiling at temperatures from 600 F. and up of petroleum oil residuum deasphaltized by one or more treatments such as atmospheric or vacuum distillation treating, acid treating and solvent treating. Such treated crude petroleum oil residuum and/or fractions thereof are further refined to wax hydrocarbons; solvent extracted to remove polycyclics, hydrogen treated to remove sulfur, nitrogen, oxygen, halogens and improve color and cold flow properties; acid treated to remove aromatics and clay treated to adsorb color and acidic materials.

To those lubricating oil base stocks there have been added alkaline earth metal salts of long chain aliphatic hydrocarbon and long chain alkyl substituted benzene sulfonic acids, alkaline earth metal alkyl substituted phenates, alkaline earth metal salts of the reaction products of P 8 with polyisobutene and polypropylenes having molecular weights of above 500 and of the hydrolysis products of the P S -polymer reaction products for their dispers ancy, anti-rust or antiwear or anti-oxidation properties. There have been also added polymeric acids, dimers of intermediate chain length unsaturated fatty acids for their anti-wear and anti-corrosion properties. Short chain (C to C alkyl substituted succinic acids and their amine derivatives (amides and imides) have been used as anticorrosion additives and long chain alkyl or alkenyl (C and above) substituted succinic acid amides and imides of polyalkylene polyamines have been used as dispersant additives. Even hydroxy substituted aliphatic acids have been used in lubricating compositions, such as a Z-hydroxy stearic acid dissolved in the lubricating oil component of greases. Sulfurized (polysulfide containing) long chain hydrocarbons, chlorinated hydrocarbons, and hydrocarbon phosphates have found use as extreme pressure additives for lubricant compositions. Such additives are well known to the art and need not be further described in detail. One common feature of those addition agents is that they all have a hydrocarbon moiety. It is with this hydrocarbon moiety that this invention is mainly concerned.

STATEMENT OF INVENTION We have discovered that lubricant addition agents, and especially the addition agents that function by forming films on the lubricated metal surfaces are increased in effectiveness when the geometry of the hydrocarbon moiety of the addition agents corresponds substantially to the geometry of the lubricant oil solvent. Such addition agents as anti-friction, anti-wear, anti-oxidant, anti-corrosion anti-rust, dispersant agents function by forming with a portion of their lubricant oil solvent an adsorbed film on the metal to be protected. Previous consideration with respect to the hydrocarbon moiety of lubricant addition agents has been directed to only the aliphatic nature and size of the hydrocarbon moiety as related to solubility and/or compatibility of the addition agent(s) with the lubricant oil. Our discovery of the increased effectiveness of addition agent solutes by having their hydrocarbon moieties correspond substantially to the geometry of the hydrocarbon lubricant oil solvent also goes to the compatibility of one addition agent with another as Well as with the lubricant oil solvent.

The concept of our invention is that, regardless of the functional group or groups on the hydrocarbon that provide the desired addition agent function in the lubricant formulation, the hydrocarbon moiety of the addition agent solute should correspond substantially in molecular geometry to the molecular geometry of the lubricating oil solvent.

To understand more clearly the geometry of the hydrocarbon portion of the lubricant addition agent solutes to obtain the improved effectiveness provided by this invention, it is essential to understand the nature of the hydrocarbons comprising lubricant oils and lubricant oil base stocks.

The lubricant oil base stocks have been classified according to their viscosities (Saybolt Universal, seconds) and assigned by the Society of Automotive Engineers (SAE) system where numbers from 5W to 250 are assigned. The relationship of viscosity in Saybolt Universal, seconds and some of these SAE base oils are shown in Table I. In general, the lubricating oil suitable for this invention are those having viscosities as low as viscosities of 140-500 SSU at 100 F. up to those having viscosities 200-250 SSU at 210 F.

TABLE I.-CORRELATION OF SAE NUMBERS AND VISCOS ITY FOR BASE STOCK OILS Viscosity, Saybolt Universal, seconds At F. At 210F.

Minimum Maximum Minimum Maximum The lubricating oil petroleum residuum fractions are difierently classified depending on the nature of the source of crude petroleum. Those residuum fractions have varying amounts of aromatics, naphthenics, and paraffins. In some the aromatic concentration exceeds the naphthenics, in others the aromatics are substantially equal to the naphthenics and in still others the naphthenics exceed the aromatics 0n the basis of aromatic rings and naphthenic rings per mole of hydrocarbon. The petroleum residuum fractions that constittue the source of lubricant oil base stocks and the base stocks are, in general, given various treatments to remove certain components whose presence is undesirable in lubricating oils. Solvent treatment removes asphaltic materials not removed by distillation of residu um. Dewaxing removes straight chain paraffins that tend to crystallize out of solution at low temperatures. Acid treating and/or solvent extraction remove a substantial portion of the aromatics. The remainder of the aromatics are converted to naphthenics by hydrotreating which also removes sulfur, nitrogen, oxygen and halogens and improves color and cold flow properties of the treated oil. Clay treatment removes acidic materials. In general, the highly resinous petroleum residuum lubricant oil fractions and/or the lubricant oil base stocks contain mainly alkyl hydrocarbon side chain substituted naphthenic ring compounds and minor amounts of branched parafiinic and alkyl substituted aromatics.

The highly refined petroleum residuum fractions constituting lubricating oil as sources for lubricant oil base stocks have hydrocarbons of from 20 to 50 carbon atoms per molecule. These hydrocarbons have alkyl hydrocarbon side chains of 7 to 20 or more carbons. Of the hydrocarbon mixture the side chains constitute 50 to 85 the naphthenic rings about 50 to 15% in the substantial absence of aromatic rings but a slightly lower amount when the aromatic rings amount to 3 to 5% as in nonhydrotreated oils. There can be even a minor amount of branched paraffinics with branch length of 7 to 12 or more carbon atoms centrally located in the parafiinic chain for such branched paraffins have rather low solidification temperatures and do not form undesirable waxy solids. Typical SAE 20 and SAE 40 oils that have not been hydrotreated have the characteristics shown in Table II.

The distillation characteristics of specific lubricating oil base stock fractions of the lubricant oil portion of Mid- Continent petroleum residuum are shown in Table III. In all cases the distillation characteristics are from distillation at 1.0 mm. Hg pressure and the temperatures shown are the boiling point for the first 1.0% distillate and for the 90% distillate.

TABLE IH.DISTILLATION CHARACTERISTICS AT 1.0 MM. HG FOR VARIOUS BASE STOCKS Distillate i i Percent Temperature, F.

10 a 20 t a a; 40 t a a;

The increased effectiveness of lubricant addition agents according to this invention can be achieved in diiferent ways. According to one embodiment, the predominant aliphatic side chain substituted naphthenic hydrocarbon in any one viscosity grade of lubricant oil is separated from the mixture comprising that viscosity grade oil and used as the hydrocarbon source for preparing the lubricant addition agent. For example, if the predominant parafiinic substituted naphthenic hydrocarbon has one naphthenic ring per molecule and a molecular weight of 320, then to obtain increased effectiveness such a substituted naphthenic hydrocarbon should be used as a starting material for the preparation of sulfonic acids, an alkylating agent (e.g., as a chloride) for the preparation of substituted benzene and phenols whose derivatives (e.g., sulfonates and phenates) are known addition agents, as a reactant (in the form of its halide) for the preparation of hydrocarbon polysulfides, as reactant for P s -hydrocarbon reaction products, halogenated hydrocarbons, etc. When halogenated on the side chain, preferably to about the monohalo content, the monohalogenated side chain parafiinic substituted naphthenates can be reacted with maleic anhydride to produce alkyl-naphthenic substituted succinic anhydride from which amides and/or imides of amines especially polyalkylene polyamines, can be prepared under amines acylation conditions that split out and remove byproduct water. The monohalogenated side chain parafllnic substituted naphthenics by reaction with alkali metal cyanide (e.g., potassium cyanide) to form the cyano-parafiinic substituted naphthenic followed by hydrolysis of the cyano group can be converted into monocarboxylic acid anti-rust agents.

The foregoing are well known reactions of substantially parafiinic hydrocarbons and are equally applicable to hydrocarbons wherein naphthenic rings have parafiinic side chains of from 50 to of the molecule. Also other known oil soluble addition agents useful in lubricating oils and greases can be prepared from such paraffinic substituted naphthenic hydrocarbons.

According to another embodiment of this invention, as the hydrocarbon portion of addition agents there can be by known methods (The Chemical Constituents of Petroleum, A. N. Sachanen, page 242 et seq., Reinhold Publishing Co., 1945), synthesized parafiinic substituted naphthenic hydrocarbons having substantially similar molecular geometry as the predominant fraction of the lubricant oil base stock in which the addition agents are to be used.

It is known that normal or slightly branched (short side chains) parafiinic hydrocarbons boiling in the range of lubricant oil distillates have low solubility at moderately low temperatures and high melting points and constitute the parafiin Waxes undesirable in lubricant oils. But these parafiin wax hydrocarbons have been used to alkylate phenols and benzenes to provide useful phenate and sulfonate lubricant oil addition agents. Also parafiinic Wax hydrocarbons have been reacted with P 5 to provide the hydrocarbon P 5 reaction product lubricant additives. However, longer side chain branched high molecular weight parafiins have low melting points and suitable lubricating viscosity characteristics that do not preclude their acceptable presence in lubricating oil base stocks. These lower melting parafiins of lubricating viscosity characteristics have side chains of at least 4 carbon atoms and when only one side chain is present the lowest melting isomers are those having the side chain centrally located on the chain. Also suitably low melting and still of acceptable lubricating viscosity characteristics are those whose C and higher branch chain are one to four carbon chain carbon atoms removed from the central chain carbon atom. Usually the lubricating oil base stocks contain little or none of those isoparafiinic hydrocarbons of acceptable low melting and lubricating viscosity characteristics. But, they can be added to lubricant oil base stocks without adversely effecting the modified base stock.

Thus, according to a still further embodiment of this invention the isoparaffins having to 50 carbon atoms boiling in the lubricating oil range and having at least one Q, or higher carbon content side chain on the central chain carbon or 1 to 4 carbon atoms removed from the central chain carbon, e.g., 11-nbutyl-docosane, 9-nbutyl-docosane, 7-n-butyl-docosane, ll-n-pentyl-heneicosane, 11-(3-pentyl)-heneicosane, l4-n-butyl-heneicosane, and the like higher carbon content isoparaifins can be used as solvents for addition agent solutes whose hydrocarbon components have substantially similar molecular geometry. For example, said isoparafiins can be the hydrocarbon portion of chloride, polysulfide, sulfonic acid including isoparafi'in substituted benzene sulfonic acid, isoparaffin substituted phenols, isoparaffin substituted succinic acid, isoparaffin-P S reaction product, isoparaffin monocarboxylic acid, etc. used per se as lubricant addition agents or used as precursors of addition agents such as the sulfonate, phenates, succinamide and succinimide types of lubricant addition agents. In the practice of this embodiment of this invention a concentrate, to by weight, of the C to C isoparafiin based lubricant addition agents as solute is dissolved in solvent C to C isoparaffin of acceptable low melting and lubricating viscosity characteristics and this concentrate is added to the lubricant oil base stock. Usually addition agents are used in low concentrations, i.e., from five percent down to 0.01 percent by weight. Thus the amount of C to C isoparafi'in solvent added to the lubricant oil base stock Will also be a minor amount not adversely affecting the general properties of the base stock oil.

The basic concept of this invention is illustrated by the following examples that demonstrate the enhancement of lubricant addition agent performance by the practice of one embodiment of this invention. The first of the examples provides a simple illustration of the practice of this invention with addition agents of a type known to be lubricant anti-rust agents. The anti-rust evaluations were made by the use of two diiferent standard test procedures. One anti-rust test used was ASTM D-665-IP /64 Rust Prevention Test where the test is conducted with distilled Water to induce rusting of the metal test rod specimens. The results of this test are reported herein under the heading ASTM Rust. The second anti-rust test used Was the Shell Film Tenacity Test developed by the Shell Oil Company Laboratories as a supplement to said ASTM Rust Prevention Test (distilled water) as is reported in Lubrication (published by The Texas Company), volume XXX, No. 5 at pages 49 and 50 (1944), and the results of this test are reported under Film- Tenacity Rust. In each test 25 solutions of 10 different anti-rust type additive solutes and two different solvents were used. The solvents were n-hexadecane and n-pentadecane. The anti-rust type additive solutes and the concentration thereof in percent by weight employed are given in Table IV with the results of each test.

TABLE IV.-RUST PREVENTION Anti-Rust Solute Weight Percent Ex. Coneen- Film-Tenacity No. Name tratlon Solvent ASTM Rust Rust 1 n-Tetradecanoic acid 0 0.4 n-Hexadecane Cm..." Moderate Severe.

acid 0. 2

2 n-Hexadecanoic acid Cm 0.4 n-Hexadecane Cm Slight.

0.2 Moderate 0.1 Severe.

3 n-Oetadecanoic acid 0 0. 4 n-Hexadecane C Slight aci 0. 2 Severe 4 2-hydroxy-n-hexadecanoic 0.1 n-Hexadecane C15"... None am 0 5. 0. 01 Slight 0.001 Severe.

5 2-hydroxy-n-octadecanoic 0.1 n-Hexadeeane Cm..." None None acid 01 0.01 do 0. 001

6 n-Pentadecanoic acid 0 5 0.4 n-Hexadeeane Cm.-. None Severe acid. 0. 2 Slight..-

7 n-Heptadecanoic acid C 0.4 n-Hexadecane Cld--- Moderate ac 0. 2 Slight 8 n-Tetradecanoic acid 014 0.4 n-Pentadecane 015.. Moderate Moderate.

acid. 0. 2 Severe 9 n-Pentadecanoic acid 01 0.4 n-Pentadecane O15. Slight Moderate.

ac 0. 2 Moderate Severe.

l0 n-Hexadecanoic acid C1 0.4 n-Pentadecane Cr5. Moderate Severe.

0.2 -do Severe, 0.5 hour.

1 Not tested.

Additive, wt. percent:

Stearic acid- Film-tenacity rust 0.1 Severe.

1.0 None. Z-hydroxystearic acid 0.01 Severe.

0.1 None.

Referring back to Table IV, it is noted that in all cases Where the geometry of the solute was same or substantially the same as the solvent the anti-rust results were enhanced (Examples 2, 4 and 9) over the results obtained when the geometry of the solvent began to depart from that of the solute.

Other applications of the basic concept of this invention appear in the example that follow.

As a starting material for the preparation of the addition agents used to prepare the lubricant oil formulation of Example 11, highly refined fraction of lubricating oil of 41 S.S.U. at 210 F., 115 viscosity index, 23% naphthenic rings, aromatic rings, 77% parafiinic side chains and an average of 1.45 rings per molecule Additive A. This hydrocarbon is reacted with P 5 (in the ratio of parts by weight of oil per part of P 8 at 300 to 320 F. in the presence of peroxide catalyst and in the presence of benzene reaction diluent for about four hours. The mixture is vigorously stirred and nitrogen passed therethrough during reaction. The reaction mixing is filtered and then reacted with 1.15 the stoichiometric amount of zinc oxide based on the amount to neutralize the acidity of the hydrocarbon-P 8 reaction product. The benzene diluent is distilled from the product.

Additive B is prepared by first sulfonating the lubricant oil fraction described in the preparation of Additive A to an average of one sulfonic acid group per molecule. The excess sulfuric acid is first converted to calcium sulfae with lime, and the calcium sulfate removed by filtration. The hydrocarbon sulfonic acid is overbased with lime in the presence of carbon dioxide gas injected into the stirred reaction mixture and in the presence of aqueous formaldehyde promoter for overbasing. The resulting reaction mixture is stirred, heated to 300 F. with CO injection to remove by-product water. The dried product is filtered. The reactants are used in amounts to give a product with a base number of about 300' as a 40% calcium soap.

Additive C is prepared by reacting maleic anhydride with the hydrocarbon defined in the preparation of Additive A at a temperature above the melting point of maleic anhydride but below its thermal decomposition temperature while bubbling chlorine through the stirred reaction mixture. A slight excess of maleic anhydride over an equimolecular proportion is used. Unreacted maleic anhydride and by products (decomposition products of maleic anhydride) are removed. This reaction mixture is cooled to 200 F. and diluted with xylene. The resulting mixture is stirred and there is slowly added thereto for each two moles of resulting substituted succinic anhydride about 0.55 mole tetraethylene pentamine. The temperature of resulting mixture increases because of the exothermic reaction. After all the polyalkylene polyamine has been added, the stirred reaction mixture is heated to remove a xylene-water azeotropic mixture and to distill off excess xylene. Then aqueous boric acid is added in an amount to provide about 1.0 boron per nitrogen and the resulting stirred mixture is heated to 280300 F. while injecting nitrogen until the product is dry, about 01-02% water or less.

A lubricant oil formulation is prepared With the following amounts of ingredients based on solvent extracted SAE 20 lubricant base stock:

Additive A to provide 2.5% by weight active zinc salt;

Additive B to provide 2.0% by weight calcium sulfonate;

Additive C to provide 5.0% by weight boron-nitrogen product.

The hydrocarbon used in the preparation of Additives A, B and C is closely related in molecular geometry to the molecular geometry of components of SAE 20 lubricant oil base stock. By the use of anti-corrosion and antioxidant Additive A, anti-rust Additive B and dispersant Additive C in said formulation because of the similarity of hydrocarbon molecular geometry between the hydrocarbon substituents of the additives and of the lubricant base stock oil enhanced effectiveness of the function of the addition agents of the same degree as before indicated may be obtained. This enhancement of additive function is, of course based on a comparison against the functional effectiveness of SAE 20 base oil solvent containing additives like Additives A, B and C except that the hydrocarbon substitutents of the comparative additives are substantially straight or slightly branched (l to 3 carbons in the branch) chain paraffinic or substantially paraffinic type substituents.

It is understood that the additives per se and their method of preparation are not part of this invention because they and their preparation are within the teachings and suggestions of the prior art. But rather the concept of having the hydrocarbon substituents of lubricant addition agent solutes conform substantially the same in molecular geometry to the molecular geometry of the hydrocarbon solvent does comprise our inventive concept.

What is claimed is:

1. A lubricant composition comprising hydrocarbon solvent consisting essentially of aliphatic hydrocarbons having at least 16 carbon atoms per molecule and dissolved therein a minor amount of lubricant addition agent solute having hydrocarbon substituents, the improvement for said lubricant composition consisting wherein said addition agent solute has a hydrocarbon substituent consisting essentially of aliphatic hydrocarbons having at least 16 carbon atoms per molecule and having molecular geometry substantially the same as the molecular geometry of the hydrocarbon solvent.

2. The composition of claim 1 wherein the hydrocarbon solvent is a petroleum hydrocarbon fraction of lubricating oil viscosity boiling above 600 F. at atmospheric pressure.

3. The composition of claim 2 wherein the solvent is a lubricating oil base stock of a viscosity in the range of SAE 5W to SAE 250.

4. The composition of claim 2 wherein the aliphatic hydrocarbon contains 20-50 carbon atoms per molecule of which 7-20 carbon atoms are in alkyl side chains.

References Cited UNITED STATES PATENTS 3,066,101 11/1962 Wilgus 25259 DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl. X.R.

P0405) UNITED STATES PATENT OFFICE CERTlFICATlL l CORREC 1 1011 Patent No. 5 I Dated Februer 3, 1970 Inventods) Herman E. Rios, Jr. and Joseph Gabor It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 6: "refined to wax hydrocarbons" should read refined to remove wax hydrocarbons Column 3, line &3: "constittue" should. be constitute and- Column 7, line +1: "sulfae" should be sulfate SIGNED AN SEALED JUN 3 0 1970 (SEAL) Amen:

Edward M. Fletcher, In mm B. BQH'UYLER, J'R. Attesting Officer fl missionar of Patents 

